It is common to store slurry, such as manure slurry on farms or effluent slurry in municipal plants, among other types, for later use or for treatment, as appropriate. Various types of slurry are typically stored in large storage tanks of perhaps thirty feet to eighty feet in diameter, or even smaller or larger, both open-top and covered-top types. Slurry is typically added to or removed from a storage tank on an intermittent basis, and is ultimately pumped from the storage tank, for transporting to another site or for use.
Slurry might remain stored in a storage tank for periods of weeks or even months at a time, and might not be added to or removed from for several days or even weeks at a time. Accordingly, it is possible for the slurry to remain immobile for several days or even weeks at a time, unless purposely agitated. Leaving slurry unagitated and immobile for days or weeks at a time can cause significant unwanted problems. The slurry tends to congeal and coagulate, and generally become lumpy, and therefore becomes very difficult to pump. Ultimately the slurry starts to solidify, which is highly undesirable, and the solids in the slurry will settle out in time, so that the lower region of the stored slurry becomes a very dense and highly viscous sludge, while the upper region of the slurry reverts to a consistency more or less like that of water.
In many instances, it is undesirable to add water to slurry to preclude it from becoming lumpy or hardening, as the addition of water tends to upset the chemical balance of the slurry. The chemical balance of the slurry is important in various applications, such as if it is to be used as fertilizer on farms. In spite of this fact, it is well known in the prior art to add water to slurry to augment agitation of the slurry.
Moreover, although it is generally undesirable to agitate slurry on an overall continuous basis because of the tremendous energy and effort required to do so, it is necessary to physically agitate slurry at least occasionally, to keep it free-flowing and liquid. Therefore, it is common to agitate slurry just before it is pumped out of its tank, perhaps immediately before or one or two days before. It is also a practice to periodically agitate slurry, so as to avoid problems as noted above; or to agitate the slurry before more slurry is added to it, so as to ensure that the stored slurry is more or less homogenous, at least for a period of time before settling once again occurs.
Since slurry is agitated on an occasional basis, it is preferable to agitate slurry in a continually moving manner in order that substantially the entire volume of slurry in a storage tank can be agitated, so as to be properly mixed and liquified. However, this is not accomplished by any apparatus in the prior art.
It is an object of the present invention to provide a slurry agitation apparatus where slurry is agitated on an occasional basis, in a continually moving manner.